The present invention relates to mountings for connecting equalizer bars to the track frames of track-laying tractors.
Track frames of track-laying tractors extend fore-and-aft along opposite sides of the tractor main frame and are connected to the latter for vertical pivotal movement about an axis which is coincident with that of final drive sprockets mounted at the rear end of the main frame. The forward ends of these track frames are interconnected by a crossbar or equalizer bar which extends transversely beneath and is pivoted medially of its ends to the main frame for pivotal movement about a fore-and-aft axis. Because the track frames and the crossbar are mounted for pivoting about different axes, the connection between the track frames and the bar must not only permit relative pivotal movement between the frames and the crossbar but also must permit the ends of the crossbar to shift both lengthwise and crosswise relative to the track frames if undue stresses are to be avoided at the connections. One known attempt at a structure for permitting such shifting movement of the crossbar ends is disclosed in U.S. Pat. No. 2,988,159 granted to Weber on June 13, 1961. Specifically, Weber shows a crossbar having cylindrical ends which are each slidably and rotatably mounted in a crossbar provided in a fore-and-aft extending cylindrical trunnion member, which is in turn rotatably and axially shiftably mounted in a bushing fixed to a respective track frame. In order for the sliding movements of the bar end and the cylindrical trunnion member to be free, the trunnion member must be disposed very nearly perpendicular to the pivot axis of the frame and at the same time very nearly parallel to the pivot axis of the equalizer bar. Thus, it is imperative that the trunnion member be precisely oriented which of course requires that close tolerances be kept.